Container closure

ABSTRACT

A safety closure for containers is particularly intended to prevent young children unscrewing caps from bottles containing medicine or poison. The closure has a screw cap which screws on the container and a safety cap which surmounts the screw cap and rotation of which in a normal position does not apply significant torque to the screw cap. Springs located and acting between the caps to provide an axial thrust bias the caps apart to the normal position determined by limiting stops. The safety cap is axially pushed down against the springs to a position where rotational coupling means on the caps can be engaged and the screw cap rotated by rotation of the safety cap. The springs are in the form of arms or tongues fixed at one end to one of the caps or to a ring interposed between the caps. The spring arms bear on one or more cap surfaces to develop the required axial thrust. As the safety cap is axially pushed down each spring arm slides on the cooperating cap surface. The latter is made concave and preferably has a curvature which increases in the direction in which the spring arm slides as the screw cap is pushed down. This feature provides an increased axial thrust in a short axial displacement.

United States Patent Kundt et al.

[4 1 Oct. 10,1972

[ CONTAINER CLOSURE Germany [73] Assignee: Ciba-Geigy AG, Basel, Switzerland [22] Filed: Feb. 5, 1971 211 Appl. No.: 113,018

[30] Foreign Application Priority Data Feb. 13, 1970 Switzerland ..2l34/70 [52] US. Cl ..2l5/9 [51] Int. Cl. ..B65d 55/02 [58] Field of Search ..2l5/9, 43 A, 46

[56] References Cited UNITED STATES PATENTS 3,341,044 9/1967 Valk ..2l5/9 3,374,912 3/1968 Velt ..2 1 5/9 3,394,829 7/1968 Peterson ..2l5/9 Primary Examiner-George T. Hall Attorney-Wenderoth, Lind & Ponack ABSTRACT A safety closure for containers is particularly intended to prevent young children unscrewing caps from bottles containing medicine or poison. The closure has a screw cap which screws on the container and a safety cap which surmounts the screw cap and rotation of s which in a normal position does not apply significant torque to the screw cap. Springs located and acting between the caps to provide an axial thrust bias the caps apart to the normal position determined by limiting stops. The safety cap is axially pushed down against the springs to a position where rotational coupling means on the caps can be engaged and the screw cap rotated by rotation of the safety cap. The

springs are in the form of arms or tongues fixed at one end to one of the caps or to a ring interposed between the caps. The spring amis bear on one or more cap surfaces to develop the required axial thrust. As the safety cap is axially pushed down each spring arm slides on the cooperating cap surface. The latter is made concave and preferably has a curvature which increases in the direction in which the spring arm slides as the screw cap is pushed down. This feature provides an increased axial thrust in a short axial displacement.

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INVENTORS EDMUND KUNDT MAX KLAIBER WILFRIED LEITZ FIG.3

ATTORNEYS CONTAINER CLOSURE This invention relates to a closure for a container.

The invention is particularly concerned with a safety closure for bottles containing medicarnents or poisonous substances, the primary purpose of such closures being to prevent a small child from being able to open the bottle. Such closures, which are sometimes known as child-proof safety closures, have been already proposed in the form of a screw cap for screwing onto a complementarily threaded container and a safety cap surmounting and substantially embracing the screw cap. Spring means are located and act between the caps to force them apart axially into a normal uncoupled position. The safety cap may be moved against the action of the spring means to a second position in which the spring means is under stress and the safety cap couples with the screw cap for rotary entrainment thereof. The spring means in one proposal comprises a plurality of arms projecting upwardly from the top of the screw cap to engage the flat inner surface of the top of the safety cap. Closures of the kind above described can be opened only by observing a prescribed sequence of operations involving displacement and rotation. It is generally desirable that such closures are not too complex in the design of the spring means and that they are functionally reliable. Embodiments of the invention are hereinafter described with these general objects in view.

In its broadest aspect the present invention now provides a closure for a container comprising a screw cap for screwing onto a complementarily threaded container; a safety cap surmounting and substantially embracing said screw cap; spring means located and acting between said caps to bias them apart axially into a first relative position; and respective means on said caps engageable in a second relative position thereof to couple said screw cap to said safety cap for rotary entrainment of said screw cap with said safety cap, said entraining means being disengaged in said first position and said second position being reached therefrom against the action of said spring means; and wherein said spring means comprises a plurality of spring arms having respective root ends fixed in a generally annular configuration about the axis of said caps and having respective portions bearing against a surface of at least one of said caps to slide therealong upon said caps being relatively moved from said first to said second position, and the or each sliding surface being concave.

In a preferred embodiment the or each sliding surface has a curvature that increases in the direction of spring sliding movement in displacing said caps from the above mentioned first to the second position.

In order that the invention and the manner of putting it into practice may be better understood a number of embodiments thereof will now be described with reference to the accompanying drawings in which the figures are all in axial section and in which:

FIG. 1 is a first embodiment of the invention, showing the caps uncoupled,

FIG. 2. is the same embodiment, showing the caps coupled,

FIG. 3 is a section taken on the line III -III in FIG. 2 on a larger scale; and

FIGS. 4 to 8 are five further embodiments, FIGS. 4, 5 and 8 being partial views.

In the figures, like parts are given like reference numerals.

Referring to the embodiment shown in FIGS. 1 to 3, the closure shown therein comprises an internally threaded screw cap 1 for screwing onto the complementarily threaded neck of a bottle or other container (not shown) to form the closure proper therefor. A safety cap 2 surmounts and substantially embraces the screw cap 1. A plurality of spring arms 3 are disposed between the upper side of cap 1 and inner top surface of cap 2 and act to bias the caps apart in an axial direction. To prevent the caps actually separating, cooperating projections 7 and 8 on caps l and 2 respectively provide stops.

The spring arms 3 are formed integrally with the cap 2, their root ends being attached to the inner top surface of the cap in a configuration which is annular about the axis of the cap. The springs extend generally in the axial direction and portions thereof including their free ends bear on one or more surfaces 4 to develop an axial thrust acting to force the caps apart. In the embodiment of FIG. 1 one annularly symmetrical surface is provided.

The caps are additionally provided with coupling means 5 and 6 for coupling the caps together so that the screw cap can be rotarily entrained with the safety cap 2 to enable the cap 1 to be unscrewed from the bottle by rotation of cap 2. In this embodiment the coupling means comprises lugs 6 on the inside of the skirt of safety cap 2 that interlock with angular counter-lugs 5 on the outer skirt surface of screw cap 1. The lugs 5 and 6 constitute a bajonet connection such that upon coupling of said lugs, the caps will be held coupled together. This is shown in detail in FIG. 3. It is apparent from FIG. 2 that the coupling means are only engageable when the safety cap 2 is pressed axially down onto the screw cap 1 against the spring action.

The sliding surface 4 against which spring arms 3 bear is concave and furthermore, the curvature increases in the direction in which the spring arms move as the safety cap 1 is displaced axially from the position of FIG. 1 to that of FIG. 2. In the normal or rest position of FIG. 1, the thrust of spring arms 3 has separeted the caps l and 2 to the limit set by stops 7 and 8. In this position safety cap 2 is freely rotatable on the screw cap 1. No significant torque can be transmitted from the safety cap to the screw cap which cannot, therefore, be unscrewed from the container (not shown) to which it has previously been screwed.

However, the safety cap 2 can be pushed down against the resistance of the springs 3. The further the safety cap is pressed down the greater the counterthrust of the springs sliding along and guided by the surface 4 since the curvature of the sliding surface increases with increasing downward displacement. By pressing down cap 2 and making a small turning motion the position shown in FIG. 2 is reached. The safety cap 2 when turned will couple with the screw cap I as shown in FIG. 3 by virtue of the cooperation of its projections 6 with peripheral counter-projections 5 on the screw cap 1. Further rotation of the safety cap 2 will now cause the screw cap 1 to be unscrewed from the container (not shown). The closure is replaced in analogous manner.

The remaining embodiments shown in FIGS. 4 to 8 have the same general features as the one just described. The description of these embodiments will, therefore, concentrate on the distinctive features of them.

In the embodiments shown in FIGS. 6 and 8, as with that of FIGS. 1 to 3, spring arms 3 are made as an integral part of the safety cap 2. The sliding surface 4 is formed in the end face of the screw cap. In FIG. 8, in contrast to FIGS. I and 2, the sliding surfaces curves outwardly from the axis in the direction of increasing curvature. The less curved portion is formed on a central upstanding and tapering neck of the screw cap 1 the top of which enters a central aperture in the top of safety cap 2. This aperture has a sufficient diameter to accommodate the neck of cap 1 as the safety cap is pressed downward.

In the embodiments according to FIGS. 4 and 5 the disposition of spring arms 3 and the sliding surfaces 4 is substantially the reverse of that illustrated in FIGS. 1, 2, 6 and 8. In these embodiments, the root ends of the spring arms are attached, and in fact are moulded integrally with, the top of screw cap 1. Their free end portions cooperate with the sliding surface 4 in the same way as has already been described.

Obviously while one circularly symmetrical sliding surface has been shown for cooperation with all the spring arms and provides all the required sliding surfaces therefore, individual sliding surfaces for the arms could be provided if desired.

So far, there has been described embodiments in which the spring arms or tongues 3 are integral with either the screw cap 1 or the safety cap 2. This construction is not essential. The springs can be a separate unit housed between the two caps. Such a construction is shown in FIG. 7.

In the embodiment according to FIG. 7 the springs 3 are borne by a separate ring 9 which is loosely interposed between the two caps I and 2. The spring arms are integral with the ring and project in the axial direction from one side of the ring. As shown, the other side of the ring 9 bears against the inside of the top of safety cap 2. Naturally the arrangement could also be reversed such that the ring 9 is supported by the screw cap 1 and the sliding surfaces 4 are on cap 2. Alternatively, a ring provided with sets of upwardly and downwardly projecting spring arms could be used, each of the two caps l and 2 then being provided with sliding surfaces for cooperation with the springs.

In the various embodiment the spring arms or tongues should preferably be so shaped that their crosssection gradually decreases from the root end to the free end.

In the embodiment according to FIG. 6 a warranty ring 10 is attached by tear-off tabs 11 to the lower skirt edge of screw cap 1. This ring is necessarily detached when the closure is opened for the first time.

In FIGS. 4, 5 and 8 the bottom part of the closure containing the coupling means is not shown. However, the coupling means may be similar to that illustrated in FIG. 1.

The container closures shown in the drawings may in principle consist of any suitable material. However with particular advantage they can be made of a synthetic thennoplastics material particularly because the springs are of simple shape and no high demands are put on the elastic properties of the spring material.

Also of particular advantage is the bajonet coupling between the two caps since this continues to hold the caps coupled together after the closure has been unscrewed, so that the closure can be quite easily replaced on the container top when desired.

The described embodiments of the invention provide a particularly satisfactory spring rate for the desired very short spring deflection, not normally attainable in simple spring arrangements. The axial displacement from the rest position of the coupled positions of the caps should be at least 2 millimeters. Owing to the favorable spring rate provided by the curvature of the sliding surface the requirements the springs arms themselves are called upon to fulfil can be very greatly reduced, both with regard to rate and fatigue. In the contemplated circumstances this is of major value because it permits all the parts of the closure, including the springs, to be made of the same material without particular regard to its spring-elastic properties. In other words, cheap plastics materials can be used for production.

What is claimed is:

l. A closure for a container comprising a screw cap for screwing onto a complementarily threaded container; a safety cap surmounting and substantially embracing said screw cap; spring means located and acting between said caps to bias them apart axially into a first relative position; and respective means on said caps engageable in a second relative position thereof to couple said screw cap to said safety cap for rotary entrainment of said screw cap with said safety cap, said entraining means being disengaged in said first position and said second position being reached therefrom against the action of said spring means; and wherein said spring means comprises a plurality of spring arms having respective root ends fixed in a generally annular configuration about the axis of said caps and having respective portions bearing against a surface of at least one of said caps to slide therealong upon said caps being relatively moved from said first to said second position, and the or each sliding surface being concave.

2. A container closure as claimed in claim I wherein the or each sliding surface has a curvature which increases in the direction of spring sliding movement in displacing said caps from said first to said second relative position.

3. A container closure as claimed in claim 2 wherein the root ends of said spring arms are attached to one of said caps and said bearing surface or surfaces are provided on the other cap.

4. A container closure as claimed in claim 1 wherein said spring arms are formed integrally with one of said caps.

5. A container closure according to claim 4 wherein said one cap and spring arms are of a plastics material.

6. A container closure as claimed in claim 1 further comprising an annular member to which the root ends of said leaf springs are attached, said annular member being disposed in the space defined between said caps.

7. A container closure as claimed in claim 6' wherein said spring arms are in two sets projecting in opposite directions from said annular member, and each of said caps providing at least one concave sliding surface, the portions of the spring arms of one and the other set cooperating with the bearing surface or surfaces of said screw cap and safety cap respectively.

8. A container closure as claimed in claim 1 wherein said entraining means is in the form of a bajonet connection.

9. A container closure as claimed in claim 8 wherein said bajonet connection comprises a set of lugs on one cap and a second set of lugs on the other cap, both sets of lugs being peripherally disposed on the respective caps, and with the individual lugs of at least one of said sets of lugs being angular.

10. A container closure as claimed in claim 2 5 wherein the axial displacement in moving said caps from said first to said second relative position is at least 2 millimeters. 

1. A closure for a container comprising a screw cap for screwing onto a complementarily threaded container; a safety cap surmounting and substantially embracing said screw cap; spring means located and acting between said caps to bias them apart axially into a first relative position; and respective means on said caps engageable in a second relative position thereof to couple said screw cap to said safety cap for rotary entrainment of said screw cap with said safety cap, said entraining means being disengaged in said first position and said second position being reached therefrom against the action of said spring means; and wherein said spring means comprises a plurality of spring arms having respective root ends fixed in a generally annular configuration about the axis of said caps and having respective portions bearing against a surface of at least one of said caps to slide therealong upon said caps being relatively moved from said first to said second position, and the or each sliding surface being concave.
 2. A container closure as claimed in claim 1 wherein the or each sliding surface has a curvature which increases in the direction of spring sliding movement in displacing said caps from said first to said second relative position.
 3. A container closure as claimed in claim 2 wherein the root ends of said spring arms are attached to one of said caps and said bearing surface or surfaces are provided on the other cap.
 4. A container closure as claimed in claim 1 wherein said spring arms are formed integrally with one of said caps.
 5. A container closure according to claim 4 wherein said one cap and spring arms are of a plastics material.
 6. A container closure as claimed in claim 1 further comprising an annular member to which the root ends of said leaf springs are attached, said annular member being disposed in the space defined between said caps.
 7. A container closure as claimed in claim 6 wherein said spring arms are in two sets projecting in opposite directions from said annular member, and each of said caps providing at least one concave sliding surface, the portions of the spring arms of one and the other set cooperating with the bearing surface or surfaces of said screw cap and safety cap respectively.
 8. A container closure as claimed in claim 1 wherein said entraining means is in the form of a bajonet connection.
 9. A container closure as claimed in claim 8 wherein said bajonet connection comprises a set of lugs on one cap and a second set of lugs on the other cap, both sets of lugs being peripherally disposed on the respective caps, and with the individual lugs of at least one of said sets of lugs being angular.
 10. A container closure as claimed in claim 2 wherein the axial displacement in moving said caps from said first to said second relative position is at least 2 millimeters.
 11. A container closure as claimed in claim 1 further comprising a warranty ring attached by tear-off tabs to the lower skirt edge of said screw cap.
 12. A container closure as claimed in claim 1 wherein said spring arm each has a decreasing cross-section from the Root end to the free end thereof. 